Remove unused MSB_FIRST defines

Makefile.libretro

@@ -78,9 +78,6 @@ else ifeq ($(platform), osx)
    TARGET := $(TARGET_NAME)_libretro.$(EXT)
    fpic := -fPIC
    SHARED := -dynamiclib
-	ifeq ($(arch),ppc)
-		ENDIANNESS_DEFINES += -DMSB_FIRST
-	endif
 	OSXVER = `sw_vers -productVersion | cut -d. -f 2`
 	OSX_LT_MAVERICKS = `(( $(OSXVER) <= 9)) && echo "YES"`
 	fpic += -mmacosx-version-min=10.1
@@ -333,7 +330,6 @@ LD   = "$(MSVCBINDIRPREFIX)/lib.exe"
 export INCLUDE := $(XEDK)/include/xbox
 export LIB := $(XEDK)/lib/xbox
 PSS_STYLE :=2
-ENDIANNESS_DEFINES += -DMSB_FIRST
 CFLAGS   += -D_XBOX -D_XBOX360
 CXXFLAGS += -D_XBOX -D_XBOX360
 STATIC_LINKING=1